1. Technical Field of the Invention
The present invention relates to novel cosmetic and/or pharmaceutical compositions for topical application to the hair and/or scalp of mammalian subjects, comprising an effective amount of at least one 2-amino-1,3-alkanediol, or derivative thereof, and to the use of such novel compositions for inducing and/or stimulating hair growth and/or retarding hair loss.
2. Description of the Prior Art
In human subjects, hair growth and its renewal are principally determined by the activity of the hair follicles. This activity is cyclical and essentially entails three phases, namely, the anagenic phase, the catagenic phase and the telogenic phase.
The active anagenic phase, or growth phase, which lasts for several years and during which the hair grows longer, is followed by a very short and transitory catagenic phase, which lasts a few weeks, and then by a resting or quiescent phase, designated the telogenic phase, which lasts a few months.
At the end of the rest period, the hair falls out and another cycle begins anew. The head of hair is thus constantly renewed and, of the approximately 150,000 hairs on a human head, at any given instant approximately 10% are at rest and will therefore be replaced in a few months.
In a significant number of cases, early hair loss occurs in genetically predisposed subjects and it affects men in particular. It is more particularly androgenetic or androgenic alopecia or, alternatively, androgeno-genetic alopecia.
This alopecia is essentially due to a disturbance in hair renewal which results, at first, in an acceleration in the frequency of the cycles at the expense of the quality of the hair and then of its amount. A progressive thinning of the head of hair occurs by regression of the so-called "terminal" hairs to the downy stage. Certain regions are preferentially affected, in particular the temple or frontal areas in men and, in women, a diffuse alopecia of the vertex is observed.
Compositions that eliminate or reduce the effects of alopecia and, in particular, that induce or stimulate hair growth or decrease hair loss have long been considered desiderata in the cosmetic and pharmaceutical industries.
In this regard, a large number of very diverse active compounds or substances have already been suggested for such purposes, for example vitamins, such as vitamin E, amino acids, such as serine or methionine, vasodilators, such as acetylcholine and derivatives thereof, female hormones, such as estradiol, keratolytic agents, such as salicylic acid, or chemical compounds, such as 2,4-diamino-6-piperidinopyrimidine 3-oxide or "Minoxidil," described in U.S. Pat. No. 4,596,812 or, alternatively, its many derivatives, such as those described in EP-353,123, EP-356,271, EP-408,442, EP-522,964, EP-420,707, EP-459,890 and EP-519,819.
Also exemplary thereof are 6-amino-1,2-dihydro-1-hydroxy-2-imino-4-piperidinopyrimidine and derivatives thereof, which are described, more particularly, in U.S. Pat. No. 4,139,619.
Nonetheless, considerable research and development is continuing in this art in quest of yet other such valuable active agents.
Minoxidil, while it remains the reference compound in the field, exhibits not insignificant side effects which complicate the use thereof.